There are simple steps to do that 

Just log in to the server.

Edit the wp-config. 

Now at the bottom you will find ('WP_DEBUG', false) just adjust those lines these 3 lines.

Whenever an error will occur, it will write to a file debug.

Hello

Debugging in WordPress is used to find any errors that are caused by any plugin or theme. It is very helpful to solve those annoying issues.

To enable debug mode in Wordpress follow the steps below

Login to your FTP account looks for the wp-config.php file in the root folder or your wordpress

and add this code

define('WP_DEBUG', true);

or else if you already see "define('WP_DEBUG', false);" just change "false" to "true"

You can also add these for logs and hide any warnings

define( 'WP_DEBUG_DISPLAY', false );
define( 'WP_DEBUG_LOG', true );

Hope this helps

Will try later, thanks.